An Experimental Study and Correlation for Differential Settling of Bidisperse Suspensions

Sedimentation processes have wide practical applications in mineral processing, metallurgical industries, chemical engineering, environmental technologies, water treatment, and bio-process engineering. The sedimentation process is complex in nature since it involves the physical properties of both the solids and the fluids forming the suspensions as well as the hydrodynamic and physico/chemical phenomena that govern particle-fluid and particle-particle behaviour. The aim of this study is to measure experimentally the lower and upper interface velocities in bidisperse suspensions of solids in liquids using liquids and solids with a wide range in physical properties, and more specifically in solids concentration (glass ballotini and sand) covering concentrated and diluted suspensions. The study covers the experimental investigations on the settling rate of bidisperse suspensions in liquids using particles of equal density and at very low particle Reynolds number (Stoke’s law region) and the voidage ranges from = 0.62 to 0.95. A correlation is developed for the representation of the experimental data for the particles of two different dimension. The experimental data have been compared with the predictions of the present proposed model as well as the models reported in the literature. An empirical correlation for 2S1 is also proposed and its dependency on the particle diameter and the concentrations is discussed

Exergy Analysis of Operating Lignite Fired Thermal Power Plant

The energy assessment must be made through the energy quantity as well as the quality. But the usual energy analysisevaluates the energy generally on its quantity only. However, the exergy analysis assesses the energy on quantity as well asthe quality. The aim of the exergy analysis is to identify the magnitudes and the locations of real energy losses, in order toimprove the existing systems, processes or components. The present paper deals with an exergy analysis performed on anoperating 50MWe unit of lignite fired steam power plant at Thermal Power Station-I, Neyveli Lignite Corporation Limited,Neyveli, Tamil Nadu, India. The exergy losses occurred in the various subsystems of the plant and their components havebeen calculated using the mass, energy and exergy balance equations. The distribution of the exergy losses in several plantcomponents during the real time plant running conditions has been assessed to locate the process irreversibility. The Firstlaw efficiency (energy efficiency) and the Second law efficiency (exergy efficiency) of the plant have also been calculated.The comparison between the energy losses and the exergy losses of the individual components of the plant shows that themaximum energy losses of 39% occur in the condenser, whereas the maximum exergy losses of 42.73% occur in the combustor.The real losses of energy which has a scope for the improvement are given as maximum exergy losses that occurredin the combustor

Thermal optical non-linearity of nematic mesophase enhanced by gold nanoparticles – an experimental and numerical investigation

In this work the mechanisms leading to the enhancement of optical nonlinearity of nematic liquid crystalline material through localized heating by doping the liquid crystals (LCs) with gold nanoparticles (GNPs) are investigated. We present some experimental and theoretical results on the effect of voltage and nanoparticle concentration on the nonlinear response of GNP-LC suspensions. The optical nonlinearity of these systems is characterized by diffraction measurements and the second order nonlinear refractive index, n 2 , is used to compare systems with different configurations and operating conditions. A theoretical model based on heat diffusion that takes into account the intensity and finite size of the incident beam, the nanoparticle concentration dependent absorbance of GNP doped LC systems and the presence of bounding substrates is developed and validated. We use the model to discuss the possibilities of further enhancing the optical nonlinearity

Kairomones of Heliothis armigera and Corcyra cephalonica and their influence on the parasitic potential of Trichogramma chilonis (Trichogrammatidae: Hymenoptera)

Kairomones from moth scales tend to influence the parasitic potential byTrichogramma chilonis Ishii. Hexatriacontane, pentacosane, heptadecane, docosane and 2, 6, l0-dodecatrienal-3, 7, 11-trimethyl were identified from the active moth scale extract ofHeliothis armigera Hubner (its natural host) andCorcyra cephalonica Stainton (a laboratory host). The significance of an array of compounds from moth scales with kairomonal activity for manipulating entomophagous insects in biological control programmes is discussed

Cross sectional study on different doses of acenocoumarol with INR in a tertiary care hospital

Background: It is of high value to be assess the relationship between doses of Acenocoumarol and the INR values to offer better patient care. Since Acenocoumarol is a commonly used drug with a narrow therapeutic range it is essential to monitor the variations encountered in response to it to avoid drastic complications and to provide better health care. Aim: The aim of this study is to compare the INR values with different doses of Acenocoumarol, to compare the association of dose of Acenocoumarol with their respective INR and to find out the occurrence of bleeding with different doses of Acenocoumarol.Methods: The study was conducted in a Tertiary care hospital. 40 patients taking Acenocoumarol were recruited in the study. Relevant details like age, weight, dose of Acenocoumarol, INR and other concomitant drugs were obtained in a prospective manner. Correlation of dose of Acenocoumarol with respective INR was done by simple linear regression.Results: The relationship between dose and INR was analyzed using Simple linear regression and the scatter plot revealed no significant correlation between the dose and INR values. There is a lot of inter-individual variability in the dose response and thereafter the INR values.Conclusions: The dose of Acenocoumarol cannot predict INR values. Patient can ideally be started treatment on a low dose of Acenocoumarol and based on the INR values, dose can be titrated. There is a need for consideration of other factors which influence the dose and INR values.

Does haemocoelom exclude embryonic stem cells and asexual reproduction in inverte­brates?

The terms embryonic and adult stem cells are explained. Previous studies on identification, description and isolation of the embryonic stem cells in different invertebrate groups are briefly summarized. Most invertebrates, which reproduce asexually have retained the embryonic stem cells in their adult body. A hypothesis is proposed for the possible exclusion of embryonic stem cells and thereby asexual mode of reproduction by the coelom in arthropods and molluscs

Cortical actin recovery at the immunological synapse leads to termination of lytic granule secretion in cytotoxic T lymphocytes.

CD8+ cytotoxic T lymphocytes (CTLs) eliminate virally infected cells through directed secretion of specialized lytic granules. Because a single CTL can kill multiple targets, degranulation must be tightly regulated. However, how CTLs regulate the termination of granule secretion remains unclear. Previous work demonstrated that centralized actin reduction at the immune synapse precedes degranulation. Using a combination of live confocal, total internal reflection fluorescence, and superresolution microscopy, we now show that, after granule fusion, actin recovers at the synapse and no further secretion is observed. Depolymerization of actin led to resumed granule secretion, suggesting that recovered actin acts as a barrier preventing sustained degranulation. Furthermore, RAB27a-deficient CTLs, which do not secrete cytotoxic granules, failed to recover actin at the synapse, suggesting that RAB27a-mediated granule secretion is required for actin recovery. Finally, we show that both actin clearance and recovery correlated with synaptic phosphatidylinositol 4,5-bisphosphate (PIP2) and that alterations in PIP2 at the immunological synapse regulate cortical actin in CTLs, providing a potential mechanism through which CTLs control cortical actin density. Our work provides insight into actin-related mechanisms regulating CTL secretion that may facilitate serial killing during immune responses

Graphene oxide as an efficient photocatalyst for photocatalytic reduction of CO2 into solar fuel

Photocatalytic reduction of CO2 into solar fuel such as methane and methanol, is an attractive approach to simultaneously solve the energy crisis and global warming problem. Herein, comparative photocatalytic activity of graphene oxide nanosheets have been investigated for photocatalytic reduction of CO2 into methane and methanol in continuous gas and liquid phase photoreactor system. The graphene oxide sheets were prepared according to Tour's method. The chemical composition and optical properties was evaluated through XPS and UV-vis spectroscopy. Graphene oxide nanosheets exhibited maximum amount of 224.87 μmol/g.h methanol and 14.8 μmol/g.h methane in liquid and gas phase system, respectively. Higher yield of methanol in liquid phase compared to methane in gaseous system can be attributed to dispersion of graphene oxide sheets in water. Hence, graphene oxide nanosheets are efficient photocatalyst for CO2 reduction into methanol. Nevertheless, further research is essential to improve the photostability of graphene oxide sheets for real application of photocatalytic CO2 reduction

Thermal Response Measurement and Performance Evaluation of Borehole Heat Exchangers: A Case Study in Kazakhstan

The purpose of the present work was to determine the thermal performance of borehole heat exchangers, considering the influences of their geometric configurations and the thermophysical properties of the soil, grout and pipe wall material. A three-dimensional model was developed for the heat and mass transfer in soil (a porous medium) and grout, together with one-dimensional conductive heat transfer through the pipe walls and one-dimensional convective heat transfer of the heat transfer fluid circulating in the pipes. An algorithm was developed to solve the mathematical equations of the model. The COMSOL Multiphysics software was used to implement the algorithm and perform the numerical simulations. An apparatus was designed, installed and tested to implement the thermal response test (TRT) method. Two wells of depth 50 m were drilled in the Almaty region in Kazakhstan. Gravel and till/loam were mainly found, which are in accordance with the stratigraphic map of the local geological data. In each well, two borehole heat exchangers were installed, which were an integral part of the ground source heat pump. The TRT measurements were conducted using one borehole heat exchanger in one well and the data were obtained. The present TRT data were found to be in good agreement with those available in literature. The numerical results of the model agreed well with the present TRT data, with the root-mean-square-deviation within 0.184 °C. The TRT data, together with the predictions of the line-source analytical model, were utilized to determine the soil thermal conductivity (λg = 2.35 W/m K) and the thermal resistance of the borehole heat exchanger from the heat transfer fluid to the soil (Rb = 0.20 m K/W). The model was then used to predict the efficiencies of the borehole heat exchangers with various geometric configurations and dimensions. The simulation results show that the spiral borehole heat exchanger extracts the highest amount of heat, followed by the multi-tube, double U-type parallel, double U-type cross and single U-type. It is also found that the spiral configuration can save 34.6% drilling depth compared with the conventional single U-type one, suggesting that the spiral configuration is the best one in terms of the depth and the maximum heat extracted. The simulation results showed that (i) more heat was extracted with a higher thermal conductivity of grout material, in the range of 0.5–3.3 W/m K; (ii) the extracted heat remained unchanged for a thermal conductivity of pipe material higher than 2.0 W/m K (experiments in the range of 0.24–0.42 W/m K); (iii) the extracted heat remained unchanged for a volumetric flow rate of water higher than 1.0 m3/h (experimental flow rate 0.6 m3/h); and (iv) the heat extracted by the borehole heat exchanger increased with an increase in the thermal conductivity of the soil (experiments in the range of 0.4–6.0 W/m K). The numerical tool developed, the TRT data and simulation results obtained from the present work are of great value for design and optimization of borehole heat exchangers as well as studying other important factors such as the heat transfer performance during charging/discharging, freezing factor and thermal interference